System and method for combustion of multiple fuels

ABSTRACT

According to embodiments, a co-fired or multiple fuel combustion system is configured to apply an electric field to a combustion region corresponding to a second fuel that normally suffers from poor combustion and/or high sooting. Application of an AC voltage to the combustion region was found to increase the extent of combustion and significantly reduce soot evolved from the second fuel.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 13/731,109, entitled “MULTIPLE FUEL COMBUSTIONSYSTEM AND METHOD,” filed Dec. 30, 2012 (docket number 2651-008-03),which claims priority benefit from U.S. Provisional Patent ApplicationNo. 61/616,223, entitled “MULTIPLE FUEL COMBUSTION SYSTEM AND METHOD,”filed Mar. 27, 2012 (docket number 2651-008-02); and is acontinuation-in-part of U.S. patent application Ser. No. 14/203,539,entitled “ELECTRICALLY-DRIVEN CLASSIFICATION OF COMBUSTION PARTICLES,”filed Mar. 10, 2014 (docket number 2651-006-03), which claims prioritybenefit from U.S. Provisional Patent Application No. 61/775,482,entitled “ELECTRICALLY-DRIVEN CLASSIFICATION OF COMBUSTION PARTICLES,”filed Mar. 8, 2013 (docket number 2651-006-02); each of which, to theextent not inconsistent with the disclosure herein, are incorporated byreference.

SUMMARY

According to an embodiment, electro-dynamic and/or electrostatic fieldsmay be applied to a co-fired combustion system to enhance combustionproperty(ies). In an example system, a bench-top scale model selectivelyintroduced an AC field across a simulated tire-derived fuel (TDF) (a cutup bicycle inner-tube) held in a crucible over a propane pre-mixedflame. Without the electric field, the simulated TDF smoked profusely.With the electric field turned on, there was not any visible soot(although instrumentation detected a low level of soot). A cause andeffect relationship was established by repeatedly turning on and turningoff the electric fields. There was no observable hysteresiseffect—switch on=no visible soot, switch off=visible soot.

According to an embodiment, a co-fired combustion apparatus may includea first fuel-introduction body defining a portion of a first combustionregion. This may correspond to the premix nozzle and a flame region, forexample. The first combustion region may be configured to combust afirst fuel (e.g., propane) in a first combustion reaction. The apparatusmay also include a second fuel-introduction body defining at least aportion of second combustion region. For example, the secondfuel-introduction body may include the crucible described above. Thesecond combustion region may be configured to combust a second fuel in asecond combustion reaction. The first combustion reaction may beoperable to sustain the second combustion reaction. For example, thesimulated TDF was not readily ignited until heated by the propane flame.An electrode assembly associated with the second combustion region maybe operable to be driven to or held at one or more first voltages. Inthe example above, the electrode assembly included the metallic crucibleitself. A grounded 4-inch stack that was located approximately axial tothe crucible may be envisioned as providing an image charge that variedto solve a field equation driven by the AC waveform.

Accordingly to another embodiment, a method of co-fired combustion mayinclude maintaining the first combustion reaction by combusting thefirst fuel at the first combustion region. In other words, the propanecombustion reaction C₃H₈+50₂→3C0₂+4H₂O may be a self-sustainingexothermic reaction. The first combustion region may have a portionthereof defined by the first fuel-introducing body. The method mayfurther include maintaining a second combustion reaction by combusting asecond fuel at a second combustion region having a portion defined by asecond fuel-introducing body. The second combustion may be sustained bythe first combustion reaction. According to embodiments, the methodincludes applying at least one first electrical potential (which mayinclude a time-varying electrical potential) proximate the secondcombustion region.

According to an embodiment, a combustion system may include a combustionvolume configured to support a combustion reaction with a fuel andoxidant, and produce a flame and a main flow of a flue gas includingentrained exhaust particles. The combustion system may further includeat least one shaped electrode acting as a corona electrode, configuredto generate a corona discharge, resulting in an ionic flow. The ionicflow may charge some of the entrained exhaust particles of the flue gas.The combustion system may further include a high voltage power supply(HVPS) configured to apply voltage to the at least one shaped electrode.

According to an embodiment, the charged exhaust particles may further beattracted to a collector plate, which may be may be formed as a singlesegment, or it may include a plurality of mechanically coupled segments.

According to another embodiment, the charged exhaust particles may bedrawn into a director conduit for recirculation back into the combustionvolume. The director conduit may further include a fan, impeller orvacuum means for facilitating the transfer of the particles.

According to yet another embodiment, the combustion system may includeboth a collector plate and a director conduit. Additionally, thecombustion system may include a combustion control system, configured tomonitor and control electric field necessary for generation of thecorona discharge, via a programmable controller operatively coupled toone or more sensors placed inside the combustion volume, and to at theat least one shaped electrode.

According to an embodiment, a method for operating a combustion systemincludes outputting a first fuel and a first oxidant, supporting a firstcombustion reaction with the first fuel and first oxidant, andsupporting a second combustion reaction of the heated second fuel to theproduce a flue gas including entrained particles. The method alsoincludes providing an electrical charge to the second combustionreaction, wherein the electrical charge is carried by the entrainedparticles, supporting a first field electrode adjacent to a main flow ofthe flue gas, applying a first voltage to the first field electrode, andelectrostatically attracting the entrained particles toward the firstfield electrode to remove at least a portion of the entrained particlesfrom a main flow of the flue gas.

According to an embodiment, a co-fired combustion apparatus, includes afirst fuel-introduction body configured to provide a first fuel to afirst combustion reaction and a second fuel-introduction body configuredto provide a second fuel to a second combustion reaction, wherein thesecond combustion reaction emits an exhaust flow having a plurality ofcombustion particle classifications and wherein the first fuelintroduction body is positioned relative to the second fuel introductionbody to cause the first combustion reaction to at least intermittentlyprovide heat to the second combustion reaction. The apparatus furtherincludes an electrode assembly associated with the second fuelintroduction body or a second combustion volume to which the second fuelintroduction body provides the second fuel, the electrode assembly beingconfigured to be driven to or maintained at one or more first voltagesselected to provide an electric field to the second combustion volume, acharge source configured to supply electrical charges into the exhaustflow, a high voltage power supply (HVPS) configured to apply anelectrical potential having a first polarity to the charge source and acollector plate including an electrical conductor coupled to receive anelectrical potential having a second polarity from a node operativelycoupled to the HVPS, the collector plate disposed above and a distal tothe second combustion reaction and arranged to cause at least onecombustion particle classification to flow to a collection location andto cause at least one different combustion particle classification toflow to one or more locations different from the collection location.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram of a co-fired combustion apparatus, according to anembodiment.

FIG. 2 is a diagram of a co-fired combustion apparatus, according to anembodiment.

FIG. 3 is a flow chart of a co-fired combustion method, according to anembodiment.

FIGS. 4-27 are thermographic images captured during a heat-exchangeexperiment wherein a voltage was applied to and removed over time from acrucible supporting a combustion, according to embodiments.

FIG. 28 depicts an embodiment of a combustion system employing a coronadischarge structure and a collector plate, according to an embodiment.

FIG. 29 shows an embodiment of a combustion system employing a coronadischarge structure and a director conduit, according to an embodiment.

FIG. 30 illustrates an embodiment of combustion system employing acorona discharge structure, a director conduit and a collector plate,according to an embodiment.

FIG. 31 shows a block diagram of a combustion control system, accordingto an embodiment.

FIG. 32 is a flow chart of a method for reducing the size and/or amountof exhaust particles entrained within a flue gas leaving a combustionsystem, according to an embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here.

FIG. 1 is a diagram of a co-fired combustion apparatus 100, according toan embodiment. The apparatus 100 may include a first fuel-introductionbody 105 defining a portion of first combustion region 110. The firstcombustion region 110 may be configured to combust a first fuel (notshown) in a first combustion reaction 115. In an embodiment, the firstfuel-introduction body 105 may be supported in a housing 120 by a firstfuel-introduction-body support 125. The first fuel may be provided by afirst fuel supply 130. The first fuel may be substantially liquid orgaseous. For example, the first fuel may include at least one of naturalgas, propane, oil, or coal. In an embodiment, the firstfuel-introduction body 105 may include a burner assembly that isconfigured to support a flame.

A second fuel-introduction body 135 may define a portion of a secondcombustion region 140. The second combustion region 140 may beconfigured to combust a second fuel 145 in a second combustion reaction150. In an embodiment, the second fuel-introduction body 135 may includea crucible assembly, which may be operable to hold the second fuel 145.Alternatively, the second fuel-introduction body 135 may include agrate, a screen, a fluidized bed support, or another apparatusconfigured to introduce, contain and/or hold the second fuel 145proximate the second combustion region 140. The second fuel-introductionbody 135 may be supported in the housing 120 by a secondfuel-introduction-body support 155. In an embodiment, the second fuel145 may be substantially solid under standard conditions. The secondfuel 145 may melt, melt and vaporize, sublime, and/or be driedresponsive to heating from the first combustion reaction 115. In anembodiment, the second fuel 145 may include one or more of rubber, wood,glycerin, an industrial waste stream, a post-consumer waste stream, anindustrial by-product, garbage, hazardous waste, human waste, animalwaste, animal carcasses, forestry residue, batteries, tires, waste plantmaterial, or landfill waste. In an embodiment, the second fuel 145 maybe fluidized to form at least a portion of a fluidized bed.

In an embodiment, the first combustion reaction 115 may sustain thesecond combustion reaction 150. For example, the first combustionreaction 115 may generate heat which initiates or supports the secondcombustion reaction 150. Accordingly, in an embodiment, the firstfuel-introduction body 105 may be positioned at a distance proximate tothe second fuel-introduction body 135 so that the first combustionreaction 115 may support the second combustion reaction 150. In anembodiment, a portion of the apparatus 100 may be enclosed within aflue, stack, or pipe configured to convey at least a portion of acombustion product stream generated by the first and/or secondcombustion reactions 115, 150.

According to an embodiment, the first combustion region 110 may besubstantially separated from the second combustion region 140. Accordingto another embodiment, the first combustion region 110 may extend tooverlap or occupy the entirety of the second combustion region 140.According to an embodiment, the first combustion reaction 115 mayprovide ignition for the second combustion reaction 150.

An electrode assembly 160 associated with the second combustion region140 may be operable to be driven to or held at one or more firstvoltages such as a constant (DC) voltage, a modulated voltage, analternating polarity (AC) voltage, or a modulated voltage with a DCvoltage offset. In an embodiment, the electrode assembly 160 may includeat least a portion of one or more of the second fuel-introduction body135, the second fuel-introduction-body support 155, the housing 120, oran electrode (not shown) separate from the second fuel-introduction body135, the second fuel-introduction body support 155, and the housing 120.In an embodiment, any of the second fuel-introduction body 135, thesecond fuel-introduction-body support 155, the housing 120, or aseparate electrode assembly 160 may each be configured to be driven toor held at one or more voltage(s), which may or may not be the samevoltage. For example, the housing 120 may be held at a ground voltageand the second fuel-introduction-body support 155 may be held at ordriven to positive and/or negative voltages. In an embodiment, thehousing 120 may rest on a grounding plate 180, which may ground thehousing 120.

It was found that the smoke reduction was most pronounced when the firstvoltage included a high voltage greater than +1000 volts and/or lessthan −1000 volts. For example, in experiments, the voltage was an ACwaveform with amplitude of +/−10 kilovolts. Other high voltages may beused according to preferences of the system designer and/or operatingengineer.

The electrode assembly 160 may be configured to be driven to or held ata voltage produced by a voltage source including a power supply 165. Thepower supply 165 may be operatively coupled to controller 170, which isconfigured to drive or control the electrode assembly 160. In someembodiments, the electrode assembly 160 may include one or moreelectrodes positioned proximate to the second combustion region 140,which may or may not directly contact the second fuel-introduction body135 or the second fuel 145. Such electrodes may be positioned in anydesirable arrangement or configuration. In an embodiment, a portion ofthe first fuel-introduction body 105, a portion of the firstfuel-introduction-body support 125, or a portion of an electrode (notshown) proximate to the first combustion region 110 may be configured tobe held at one or more second voltage(s).

The apparatus 100 may optionally include one or more sensor(s) 175operable to sense one or more conditions of the apparatus 100,components thereof, and/or the second fuel 145 combustion reaction 150.For example, a sensor 175 may sense heat, voltage, fluid flow, fluidturbulence, humidity, particulate matter, or one or more compounds orspecies. In an embodiment, the sensor 175 may be used to sense thecondition or state of a combustion product stream generated by thesecond combustion reaction 150. A sensed state or condition of thecombustion product stream generated by the second combustion reaction150 may be used by a feedback controller 170 to modify or modulate theone or more voltages and/or waveforms that the electrode assembly 160 isheld at or driven to.

For example, as further discussed herein, driving or holding theelectrode assembly 160 at one or more voltages may affect the secondcombustion reaction 150. Driving or holding the electrode assembly 160at one or more voltages may modify the efficiency, rate, thermal output,or turbulence, of the second combustion reaction 150. The sensor(s) 175may be operable to detect such effects.

It was found that applying an electric field proximate to a combustionreaction may be used to improve the efficiency of the combustionreaction. The improvement in efficiency may include a reduction inundesirable combustion products such as unburned fuel, oxides of sulfur(SO_(X)), oxides of nitrogen (NO_(X)), hydrocarbons, and other species.Additionally, the improvement in efficiency may include an increase inthermal energy generated by the combustion reaction per the amount offuel. In addition to being less harmful to the environment, supporting acleaner combustion reaction may result in lower operating expense.Discharge of certain combustion pollutants may require the purchase ofemission-permits for an amount of pollutant discharge. Reducingpollutant discharge in a given reaction may therefore allow a businessto obtain fewer emission-permits and/or output more heat at a reducedcost. Additionally or alternatively, less fuel may be consumed togenerate an equivalent amount of energy.

Increased efficiency of a combustion reaction may occur via one or moremechanisms. For example, applying an electric field proximate to acombustion reaction may increase the number of collisions betweenreactants, which may increase the reaction rate. In one example,applying an electric field proximate to a combustion reaction mayincrease the collision energy of reactants and therefore increase therate of reaction. In another example, applying an electric fieldproximate to a combustion reaction may provide a self-catalysis effectfor various desirable reactions and may reduce the reaction activationenergy by urging reactants to come together in a correct reactionorientation. In a further example, applying an electric field proximateto a combustion reaction may increase the turbulence of a reaction andthereby increase the mixture or introduction rate of reactants (e.g.,increased mixing of oxygen with fuel), which may promote a moreefficient or complete combustion reaction (e.g., where reactants combustto produce a greater proportion of desired reaction products, fewerunreacted reactants and undesired products or by-products of thecombustion reaction will be emitted).

FIG. 2 is a diagram of a co-fired combustion apparatus 200, according toan embodiment. The apparatus 200 may include a first fuel-introductionbody 105 defining a portion of first combustion region 110. The firstcombustion region 110 may be configured to combust a first fuel from afirst fuel supply 130 in a first combustion reaction 115. In anembodiment, the first fuel-introduction body 105 may be supported in ahousing 120 by a first fuel-introduction-body support 125.

The apparatus 200 may also include a second fuel-introduction body 135defining a portion of a second combustion region 140. The secondcombustion region 140 may be configured to combust a second fuel (notshown) in a second combustion reaction (not shown). In an embodiment,the second fuel-introduction body 135 may include a crucible assembly,which may be configured to hold the second fuel. Alternatively, thesecond fuel-introduction body 135 may include a grate, a screen, afluidized bed support, or another apparatus configured to introduceand/or contain or hold the second fuel proximate the second combustionregion 140. The apparatus may also include a stoker 210, configured tointroduce the second fuel to the fuel-introduction body 135.

For example, in an embodiment, the second fuel may include timber wasteproducts, and the stoker 210 may be configured to convey timber wasteproducts into the fuel-introduction body 135 so that sufficient secondfuel is present to sustain a relatively constant combustion fuel volumewithin the second fuel-introduction body 135. For example, as the secondfuel is consumed, additional second fuel may be introduced by the stoker210 so that the second combustion reaction may continue. Optionally, thesecond fuel-introduction body 135 may include a containment body 160Bconfigured to prevent entrainment of unburned second fuel particles influe gas exiting through the top of the body 120.

In another embodiment, the second fuel may include black liquor, such asa residue from a sulfite pulp mill. The stoker 210 may be configured toconvey liquid or semi-solid black liquor to the second combustion region140.

Optionally, the burner 200 may include a heat recovery system includingone or more heat transfer surfaces such as water tube boiler tubes toconvert heat output by the second (not shown) and/or first combustionreaction 115 to heated water or steam. According to an embodiment, theapplication of electrical energy to at least the second combustionreaction (not shown) may reduce tendency for combustion byproducts orentrained materials to be deposited on heat transfer surfaces. This mayallow a longer operating duration between service shut-downs to cleanheat transfer surfaces.

A first and second electrode assembly 160A, 160B associated with thesecond combustion region 140 may be operable to be driven to or held atone or more voltages using a substantially constant (DC) voltage, amodulated voltage, an alternating polarity (AC) voltage, or a modulatedvoltage with DC voltage offset. The first electrode 160A assembly may beconfigured to be driven to or held at one or more first voltages. Thesecond electrode 160B assembly may be configured to be driven to or heldat one or more second voltages. In an embodiment, the first and secondone or more voltages may be the same. The first and second electrodeassemblies 160A, 160B may be electrically isolated from a portion of thehousing 120 via respective insulators and/or air gaps 220A, 220B. In anembodiment, the first and second electrode assembly 160A, 160B may beheld or driven to a first and second voltage respectively, and thehousing 120 may be held at or driven to a third voltage. For example,the housing 120 may be held at ground potential via a grounding plate180.

The first and second electrode assembly 160A, 160B may each beconfigured to be driven to or held at a voltage produced by a voltagesource including a power supply 165. The power supply 165 may beoperatively coupled to controller 170, which may be configured tocontrol the output voltage, current, and/or waveform(s) output by thepower supply 165 to the first and/or second electrode assemblies 160A,160B.

The apparatus 200 may optionally include a first and/or second sensor170A, 1706 operable to sense one or more conditions of the apparatus 200or components thereof. For example, the first sensor 170A may beassociated with the first electrode assembly 160A, and the second sensor170B may be associated with the second electrode assembly 160B.

FIG. 3 is a flow chart showing a method 300 for operating a co-firedcombustion system, according to an embodiment. The method 300 begins inblock 310 where a first combustion is maintained at a first combustionregion by combusting a first fuel. For example, referring to FIGS. 1 and2, the first combustion 115 may be maintained at the firstfuel-introduction body 105 in the first combustion region 110. The firstfuel may be a relatively free-burning fuel such as a hydrocarbon gas, ahydrocarbon liquid, or coal. The first fuel should be chosen to have aflame temperature that is sufficiently high to support and/or ignitecombustion of the second fuel.

The method 300 continues in block 320, where a second combustionreaction is sustained by heat and/or ignition from the first combustionreaction. The second combustion reaction may be maintained at a secondcombustion region by combusting the second fuel. For example referringto FIGS. 1 and 2, the second combustion reaction 150 may be sustained bythe first combustion reaction 115, at the second fuel-introduction body135 in the second combustion region 140. According to an embodiment,heat from the first combustion reaction may dry, volatilized, and/orraise a vapor pressure of the second fuel sufficiently to allow thesecond fuel to burn. Additionally or alternatively, the first combustionregion may overlap with or contain the second combustion region. Thefirst combustion reaction may provide ignition and/or maintaincombustion of the second fuel.

The method 300 continues in block 330 where a first potential orsequence of potentials is applied to a first electrode operativelycoupled to the second combustion region. For example, referring to FIG.1 a first potential or sequence of potentials may be applied to theelectrode assembly 160 proximate to the second combustion region 140.Referring to FIG. 2, a first potential may be applied to the firstelectrode assembly 160A proximate to the second combustion region 140.According to an embodiment, the first potential or sequence ofpotentials may include a substantially constant (DC) voltage, amodulated voltage, an alternating polarity (AC) voltage, or a modulatedvoltage with DC voltage offset.

The method 300 continues in block 340, where a second electricalpotential or sequence of potentials is applied to a second electrodeoperatively coupled to the second combustion region. For example,referring to FIG. 1 a second potential may be applied to the housing 120proximate to the second combustion region 140. Referring to FIG. 2, asecond potential may be applied to the second electrode assembly 160Bproximate to the second combustion region 140.

The electrical potentials applied in steps 330 and 340 may be selectedto cause an increase in reaction rate and/or an increase in the reactionextent reached by the second combustion reaction. According to anembodiment, the first electrical potential or sequence of potentials mayinclude a time-varying high voltage. The high voltage may be greaterthan 1000 volts and/or less than −1000 volts. According to anembodiment, the high voltage may include a polarity-changing waveformwith an amplitude of +/1 10,000 volts or greater. The waveform may be aperiodic waveform having a frequency of between 50 and 300 Hertz, forexample. In another example, the waveform may be a periodic waveformhaving a frequency of between 300 and 1000 Hertz. According to anembodiment, the second electrical potential may be a substantiallyconstant (DC) ground potential.

The method is shown looping from step 340 back to step 310. In a realembodiment, the steps 310, 320, 330, and 340 are generally performedsimultaneously and continuously while the second fuel is being burned(after start-up and before shut-down).

EXAMPLE

Referring to FIG. 1, a burner assembly 105 was disposed within acylindrical housing 120, defining a first combustion region 110. Theburner assembly 105 was operatively connected to a propane gas supply(first fuel supply 130), which was used to sustain a propane flame onthe burner assembly 105 in a first combustion 115. The housing 120 wasapproximately 3 inches in diameter and approximately 1 foot tall. Theburner assembly 105 was substantially cylindrical having a diameter ofapproximately ¾ inch, and a height of approximately 1 inch.

A crucible 135 having a diameter of approximately ¾ inch was positionedwithin the housing 120 above the propane first combustion 115. Thecrucible 135 held a mass of rubber pieces (second fuel 145), which wereobtained by cutting pieces from a bicycle inner-tube. The propane firstcombustion 115 caused the rubber pieces to ignite, thus generating asecond combustion 150. The second combustion 150 of the rubber piecesgenerated a combustion product stream (not shown), which visuallypresented as black smoke. The housing 120 was used to contain and directthe combustion product stream, and rested on a grounding plate 180,which held the housing 120 at a ground voltage.

A modulated voltage of 10 kV was then applied to the crucible 135 at afrequency of 300-1000 Hz. The smoke generated by the combustion of therubber pieces changed from a black smoke to no visible smoke. Thisindicated that the combustion product stream included fewerparticulates. The voltage was removed from the crucible 135 and thecombustion product stream again presented as black smoke. The voltagewas again applied to the crucible 135 and the combustion product streamagain presented as a lighter or substantially no visible smoke.

In a first particulate-residue trial, a first volume of rubber pieceswas burned in the crucible 135 and a first paper filter was positionedon the top end of the housing 120 to collect particulate matter in thecombustion product stream. A voltage was not applied to the crucible135.

In a second particulate-residue trial, a second volume of rubber pieces(having substantially the same mass as the first volume of the firsttrial) was burned in the crucible 135 and a second paper filter waspositioned on the top end of the housing 120 to collect particulatematter. A modulated voltage of 10 kV was then applied to the crucible135 at a frequency of 300-1000 Hz.

The first and second filter papers were compared, and the first filterpaper exhibited a substantial layer of black particulate matter. Thesecond filter paper on exhibited a light discoloration of the paper, butdid not have a layer of particulate matter. This result furtherindicated that the application of the voltage created a substantialreduction in particulate matter in the combustion product stream of thecombusting rubber pieces.

In a first heat-exchange trial, a first volume of rubber pieces wasburned in the crucible 135 and thermographic images of the combustionwere recorded over time using a Fluke Ti20 Thermal Analyzer at aperspective substantially the same as the perspective of FIG. 1. Apropane fuel volume of 0.4 actual cubic feet per hour (acfh) wassupplied to the burner assembly 105 during the trial. A voltage was notapplied to the crucible 135.

In a second heat-exchange trial, a second volume of rubber pieces(having substantially the same mass as the first volume of the firsttrial) was burned in the crucible 135 and thermographic images of thecombustion were recorded over time using a Fluke Ti20 Thermal Analyzerat a perspective substantially the same as the perspective of FIG. 1. Apropane fuel volume of 0.2 actual cubic feet per hour (acfh) wassupplied to the burner assembly 105 during the trial (i.e., half of thefuel compared to the first trial). A modulated voltage of 10 kV was thenapplied to the crucible 135 at a frequency of 300-1000 Hz.

The thermographic images of the first and second heat-exchange trialwere compared over time. At 15 seconds, both burners registeredapproximately 130° F. At 45 seconds the first heat-exchange trialcontinued to register 130° F.; the second heat-exchange trial burner(with 50% fuel) registered approximately 186° F. These trials indicatedthat even with 50% fuel volume, application of a voltage to the crucible135 generated a higher combustion temperature.

In a third heat-exchange trial, a volume of rubber pieces was burned inthe crucible 135 and thermographic images of the combustion wererecorded over time using a Fluke Ti20 Thermal Analyzer at a perspectivesubstantially the same as the perspective of FIG. 1. Over time, amodulated voltage of 10 kv was then applied to the crucible 135 at afrequency of 300 Hz for a period of time; the voltage was removed for aperiod of time; a modulated voltage of 10 kv was then applied to thecrucible 135 at a frequency of 1000 Hz for a period of time; and thevoltage was removed for a period of time. The application and removal ofthese voltages was repeated six times. An image was captured at the endof each period.

FIGS. 4-27 depict the thermographic images captured during theheat-exchange trial from a time of 9:27:16 until 10:52:16 and show thatapplication of a voltage to the crucible 135 generated a highercombustion temperature.

Schlieren photography was used to visualize the flow of the combustionproduct stream generated by the combustion of rubber pieces within thecrucible 135. When no voltage was applied to the crucible 135, the flowof the combustion product stream appeared to be laminar flow; however,when a modulated voltage of 10 kV was then applied to the crucible 135at a frequency of 300-1000 Hz, the combustion product stream appeared tohave turbulent flow. In other words, the combustion product streambehaved according to a low Reynolds number, laminar flow regime when novoltage was applied, and exhibited a high amount of turbulence evocativeof a high Reynolds number when a voltage was applied, even though massflow rates were nearly identical.

With reference to FIGS. 1-3, According to an embodiment, a co-firedcombustion apparatus 100 may include a first fuel-introduction body 105configured to provide a first fuel (not shown) to a first combustionreaction 115, and a second fuel-introduction body 135 configured toprovide a second fuel 145 to a second combustion reaction 150. The firstfuel introduction body 105 may be positioned relative to the second fuelintroduction body 135 to cause the first combustion reaction 115 to atleast intermittently provide heat to the second combustion reaction 150.The co-fired combustion apparatus 100 may further include an electrodeassembly 160 associated with the second fuel introduction body 135 or asecond combustion volume to which the second fuel introduction body 135provides the second fuel 145. The electrode assembly 160 may beconfigured to be driven to or maintained at one or more first voltagesselected to provide an electric field to the second combustion volume.The electrode assembly 160 may include one or more electrodes proximateor within the second combustion region 140. Additionally, it may includethe second fuel-introduction body 135.

A portion of the apparatus may be enclosed within a housing 120. Theportion of the housing 120 may be operable to be driven to or held atone or more second voltages. In an embodiment, the electrode assembly160 may include a portion of the housing 120. Additionally oralternatively, the electrode assembly 160 may include the secondfuel-introduction body 135. The second fuel-introduction body 135 mayinclude a crucible assembly configured to support the second fuel 145.In an embodiment, the electrode assembly 160 may include the crucibleassembly.

According to an embodiment, the first fuel-introduction body 105 mayinclude a burner assembly. Additionally, the first fuel-introductionbody 105 may be operable to be driven to or held at one or more secondvoltages. The electrode assembly 160 associated with the secondcombustion region 140 may be operable to increase combustion efficiencyof the second combustion when the electrode assembly 160 is driven to orheld at the one or more first voltages. The second combustion mayproduce a combustion product stream having a flow, wherein the electrodeassembly 160 associated with the second combustion region 140 may beoperable to generate a combustion product stream flow having turbulentflow when the electrode assembly 160 is driven to or held at the one ormore first voltages.

According to an embodiment of a co-fired combustion apparatus, the firstfuel may be substantially liquid or gaseous, whereas the second fuel 145may be substantially solid. For example, the first fuel may include atleast one of natural gas, propane, butane, coal, or oil. The second fuel145 may include one or more of rubber, wood, glycerin, an industrialwaste stream, a post-consumer waste stream, an industrial by-product,garbage, hazardous waste, human waste, animal waste, animal carcasses,forestry residue, batteries, tires, waste plant material, or landfillwaste. Additionally, the second fuel 145 may form a portion of afluidized bed.

In an embodiment, a co-fired combustion apparatus may include a stoker210 configured to introduce the second fuel 145 to the second combustionregion 140.

In an embodiment, a portion of the co-fired apparatus may be enclosedwithin a flue, stack, or pipe configured to convey a combustion productstream generated by at least the second combustion.

In an embodiment, the co-fired combustion apparatus may further includea first burner assembly configured to support the first combustion, anda burner support configured to support the first burner assembly in ahousing 120.

According to an embodiment, a method of co-fired combustion may includestep maintaining a first combustion by combusting a first fuel at afirst combustion region having a portion defined by a firstfuel-introducing body, step maintaining a second combustion bycombusting a second fuel at a second combustion region having a portiondefined by a second fuel-introducing body, the second combustionsustained by the first combustion, and step applying at least one firstelectrical potential proximate to the second combustion region. Themethod of co-fired combustion may further include step applying at leastone second electrical potential proximate to the first combustionregion. Additionally or alternatively, the method may also includeapplying at least one second electrical potential at another locationproximate to the second combustion region.

In an embodiment, the method of co-fired combustion may includeconveying a combustion product stream generated by at least the secondcombustion through a flue, stack or pipe.

According to an embodiment of the method of co-fired combustion, anelectrode assembly may be operable to apply the at least one firstelectrical potential. The electrode assembly may include one or moreelectrodes proximate to the second combustion region. The electrodeassembly associated with the second combustion region may be operable toincrease combustion efficiency of the second combustion when theelectrode assembly applies the one or more first electrical potential,compared to not applying the one or more first electrical potential.

According to an embodiment of the method of co-fired combustion, thesecond combustion may produce a combustion product stream includingparticulates. The electrode assembly associated with the secondcombustion region may be operable to increase combustion of theparticulates in the combustion product stream when the electrodeassembly applies the one or more first electrical potential. The secondcombustion may produce a combustion product stream having a flow,wherein applying the first electrical potential proximate to the secondcombustion region may be operable to generate a combustion productstream flow having greater turbulence than another flow havingsubstantially equal Reynolds number with no electrical potentialapplied.

Additionally, the second fuel may be introduced to the second combustionregion with a stoker. In an embodiment, the first fuel may besubstantially liquid or gaseous, and the second fuel may besubstantially solid. Additionally or alternatively, the second fuel mayinclude one or more of rubber, wood, glycerin, an industrial wastestream, a post-consumer waste stream, an industrial by-product, garbage,hazardous waste, human waste, animal waste, animal carcasses, forestryresidue, batteries, tires, waste plant material, or landfill wastematerial. The first fuel may include natural gas, propane, butane, coalor oil.

As used herein, the following terms may have the following definitions:

“corona discharge” may refer to an electrical discharge, either positiveor negative, produced by the ionization of a fluid surrounding anelectrically energized conductor.

“ionic wind” may refer to a stream of ions generated from a tipelectrode by a strong electric field exceeding a corona dischargevoltage gradient and that may be used to charge exhaust combustionparticles.

FIG. 28 depicts an embodiment of a combustion system 2100 employing acorona discharge device using at least two sharp shaped electrodes 2106,i.e., electrodes that taper to a sharp tip directed outward toward thecombustion exhaust gases 2103 and a collector plate 2102, according toan embodiment. Suitable materials for the collector plate 2102 mayinclude conductive materials such as iron, steel (such as stainlesssteel), copper, silver or aluminum or alloys of each of these metalsprovided that the preponderant constituent of the alloy consists ofiron, steel, copper, silver or aluminum. Combustion itself may beprovided for though a variety of fuels such as solid, liquid and gashydrocarbon fuels together with various oxidizers, the most common beingambient air. Other fuel and oxidizer combinations are also possible.

In order to accomplish a simultaneous charging and collection of exhaustparticles 2104, electrodes 2106 may be placed at either side of acombustion volume 2108 above flame 2101, and charged with a sufficientlyhigh voltage to generate a corona discharge. Voltage may be applied toelectrodes 2106 by a high voltage power source (HVPS) 2110.

In order to generate a corona discharge one or both electrodes 2106 isconfigured to taper to a sharp tip, which can produce a projection ofions near the end of this tip when excited by voltages above a minimumionization limit. Corona discharge is a process by which a current flowsfrom one electrode 2106 with a high voltage potential into a zone ofneutral atmospheric gas molecules such as is present in the combustionexhaust gases 2103 adjacent to the tips of electrodes 2106. Theseneutral molecules can be ionized to create a region of plasma aroundelectrode 2106. Ions generated in this manner may eventually pass chargeto nearby areas of lower voltage potential, such as at collector plate2102, or they can recombine to again form neutral gas molecules.

When the voltage potential gradient, or electric field, is large enoughat a point in the area where a corona discharge is established, neutralair molecules may be ionized and the area may become conductive. The airaround a sharp shaped electrode 2106 may include a much higher voltagepotential gradient than elsewhere in the area of neutral air molecules.As such, air near electrodes 2106 may become ionized, while air in moredistant areas may not. When the air near the tips of sharp shapedelectrodes 2106 becomes conductive, it may have the effect of increasingthe apparent size of the conductor. Since the new conductive region maybe less sharp, the ionization may not extend past this local area.Outside this area of ionization and conductivity, positively charged airmolecules may move in the direction of an oppositely charged object suchas collector plate 2102, where they may be neutralized and/or collected.

The movement of these ions generated by a corona discharge, therefore,may form an ionic wind 2114. When exhaust particles 2104 pass throughionic wind 2114, ions may be attached to some or all of exhaustparticles 2104 such that particles 2104 become positively charged toprovide charged particles 2112.

When the geometry and voltage potential gradient applied to a firstconductor increase such that the ionized area continues to grow until itcan reach another conductor at a lower potential, a low resistanceconductive path between the two conductors may be formed, resulting inan electric arc.

Corona discharge, therefore, may be generally formed at the highlycurved regions on electrodes 2106, such as, for example, at sharpcorners, projecting points, edges of metal surfaces, or small diameterwires. This high curvature may cause a high voltage potential gradientat these locations on electrodes 2106 so that the surrounding air breaksdown to form a plasma. The electrodes 2106 are preferably driven to avoltage sufficiently high to eject ions, but sufficiently low to avoidcausing dielectric breakdown and associated plasma formation. The coronadischarge may be either positively or negatively charged depending onthe polarity of the voltage applied to electrodes 2106. If electrodes2106 are positive with respect to collector plate 2102, the coronadischarge will be positive and vice versa. Typically charges of eithersign are deposited on molecules and/or directly onto largerparticulates. Charges deposited onto molecules tend to transfer tolarger particles (e.g. onto particles including carbon chains with arelatively large number of carbon atoms). Particles including carbonchains essentially constitute unburned fuel. It is desirable to recyclecarbon into the combustion reaction to achieve more complete combustion.

Moreover, charges tend to collect on metals and metal-containingparticulates including mercury, arsenic, and/or selenium. According toembodiments, structures and functions disclosed herein are arranged toremove metal cations from flue gas.

In some embodiments, ions in ionic wind 2114 can have a constantpositive polarity. Positively charged particles 2112 may be attracted bycollector plate 2102 which may be negatively charged. Particles 2104which are larger may obtain more charge due to a larger area exposed toreceive more positive ions, for example. Charged particles 2112 sizedbetween about 0.1 μm and about 10 μm may be more easily attracted andcollected by collector plate 2102, while charged particles 2112 withsize smaller than about 0.1 μm can exit combustion system 2100 withoutbeing attracted by collector plate 2102. Re-entrainment of chargedparticles 2112 larger than 10 μm into combustion volume 2108 or disposalwithin a suitable storage component of combustion system 2100 (notshown) may reduce exhaust emissions, including but not limited to sootand unburned fuel that may be contained within particles 2104.

In other embodiments, ions in ionic wind 2114 can have a negativepolarity.

In still other embodiments, charging the combustion reaction can beomitted. A collector plate 2102 or director conduit 202 (see FIG. 29)can attract charged particles such as metal cations from the flue gas.

Other charging methods can, for example, include utilizing fluxes ofx-rays or laser beams, radiation material enrichment-like processes, andvarious electrical discharge processes. The application of an electricfield by a corona discharge generated by an application of high voltageat electrodes 2106 may be controlled by a combustion control system.

According to another embodiment, the collector plate 2102 may include anelectrical conductor coupled to receive a second polarity electricalpotential from a node (not shown) operatively coupled to the HVPS 2110.The collector plate 2102 may be disposed above and away from thecombustion volume 2108 distal to the flame 2101, arranged to cause atleast one particle classification to flow to a collection location andto cause at least one different particle classification to flow to oneor more locations different from the collection location. The mainparticle flow may typically be aerodynamic. The differentiation betweenthe collected particles and uncollected particles may be based at leastpartly on the response of a characteristic charge-to-mass ratio (Q/m) ofthe collected particles.

In yet another embodiment, a director conduit may be configured toreceive the flow of the selected particle classification at a firstcollection location and to convey the flow of at the least one particleclassification to an output location. The output location may beselected to cause the output flow of the selected particleclassification to flow back toward the flame 2101. For example, unburnedfuel particles may be relatively heavy, and have a tendency to carrypositive charges on their surface. According to yet another embodiment,the described system can recycle the unburned fuel to the flame 2101.For example, this can allow higher flow rates than could normally besustained with high combustion efficiency.

FIG. 29 shows an embodiment of a combustion system 2200 employing acorona discharge device, as described in FIG. 28, and the directorconduit 2202. Particles 2104 charged by ionic wind 2114 generated by acorona discharge created by the application of a high voltage toelectrodes 2106, provide charged particles 2112, in an embodiment.Charged particles 2112 may exit combustion volume 2108 and may beattracted to director conduit 202 which may be polarized or groundedsuch that director conduit 202 may be negatively charged with respect topositively charged particles 2112. A fan or impeller 204 may be placedinside director conduit 202 to provide additional dragging force toattract charged particles 2112 back into combustion volume 2108 wherecharged particles 2112 may be re-burned or disposed of into a suitablestorage location (not shown) in combustion system 2200. As described inFIG. 28, larger particles 2104 may obtain more charge than smallerparticles 2104, therefore, particles 2104 of a size raging from about0.1 μm to about 10 μm may be more easily attracted to director conduit2202. After re-burning, charged particles 2112 may be consumed or may beagglomerated to a size larger than about 0.1 μm, and thus may exitcombustion system 2200 without being attracted by director conduit 2202.Fan or impeller 2204 may generate a vacuum pressure selected to reducesedimentation of charged particles 2112 in director conduit 2202.Suitable materials for director conduit 2202 may include a variety ofinsulated and/or dielectric materials such as elastomeric foam,fiberglass, ceramics, refractory brick, alumina, quartz, fused glass,silica, VYCOR™, and the like.

In still another embodiment, FIG. 30 illustrates a combustion system2300 employing a corona discharge device and a collector plate 2102, asdescribed in FIG. 28, and a director conduit 202, as described in FIG.29. Particles 2104 may again be charged by ionic wind 2114 generated bya corona discharge created by the application of a high voltage toelectrodes 2106 to provide charge particles 2112. The charged particles2112 may exit combustion volume 2108 and may be attracted to directorconduit 2202 which may be polarized or grounded such that directorconduit 2202 may be negatively charged with respect to positivelycharged particles 2112. As before, director conduit 2202 may include aninlet port disposed above the combustion volume, an outlet port disposedadjacent to the flame, a tubular body between the inlet and outletports. Fan or impeller 2204 may be placed inside director conduit 202 toprovide additional dragging force to draw charged particles 2112 backinto combustion volume 2108 where charged particles 2112 may bere-burned. Fan or impeller 2204 may also generate a vacuum pressurewhich may reduce sedimentation of charged particles 2112 in directorconduit 2202. Suitable materials for director conduit 2202 may againinclude insulated and dielectric materials such as elastomeric foam,fiberglass, ceramics, refractory brick, alumina, quartz, fused glass,silica, VYCOR™, and the like.

Finally, particles 2104 in exhaust gases that are recirculated troughflame 2101 and re-burned may be charged again during another cycle ofcorona discharge application and may be collected by collector plate2102 for later disposal according to established methods for exhaust gasemissions.

FIG. 31 is a block diagram of combustion control system 2400 that may beintegrated in combustion systems 2100, 2200, and 2300, according to anembodiment. Programmable controller 2402 may determine and control thenecessary electric field for the generation of a corona discharge fromHVPS 2110 to apply suitable voltages to electrodes 2106 based oninformation received from sensors 2404. Sensors 2404 may be placedinside combustion volume 2108 to send feedback to programmablecontroller 2402 to determine the voltage potential gradient required toestablish the corona discharge. Combustion control system 2400 mayinclude a plurality of sensors 2404 such as combustion sensors,temperature sensors, spectroscopic and opacity sensors, and the like.The sensors 2404 may also detect combustion parameters such as, forexample, a fuel particle flow rate, stack gas temperature, stack gasoptical density, combustion volume temperature and pressure, luminosityand levels of acoustic emissions, combustion volume ionization,ionization near one or more electrodes 2106, combustion volumemaintenance lockout, and electrical fault, amongst others. Theinformation (sensor output data) provided by the plurality of sensors2404 may be typically in the form of continuous, discrete voltage outputdata (e.g., ±5V, ±12V) several times a second which is compared againstpredetermined (preprogrammed) values, in real time, within programmablecontroller 402.

FIG. 32 is a flow chart of a method 2500 for reducing the size andnumber of particles entrained within an exhaust flow leaving acombustion system, according to an embodiment. The method 2500 includesstep 2502, a first electrical potential is applied to one or more shapedelectrodes positioned above a flame within a combustion volume andadjacent to an exhaust flow including a plurality of burned and unburnedparticles leaving the combustion volume. The one or more shapedelectrodes may be tapered to a sharp tip directed into the exhaust flow.The applied electrical potential may generate a corona dischargedproximate to the sharp tip of each of the one or more shaped electrodes.The corona discharge may generate an ionic wind passing through theexhaust flow. A portion of the plurality of burned and unburnedparticles may acquire an electric charge having a first polarity.

In step 2504 an electrically conductive collector plate is provided. Thecollector plate may be disposed above and away from the combustionvolume distal to the flame.

In step 2506, a second electrical potential is applied to theelectrically conductive collector plate. The second electrical potentialmay have a polarity opposite that of the first polarity, wherein somefraction of the plurality of the charged particles may be collected at asurface of the collector plate.

In step 2508, a “flow” or director conduit is provided. The directorconduit may include an inlet port disposed above the combustion volume,an outlet port disposed adjacent to the flame, a tubular body betweenthe inlet and outlet ports, and a fan, impeller or vacuum means fordrawing some portion of the exhaust flows through the tubular bodythereby redirecting some portion of the burned and unburned particlesnot captured by the collector plate back into the combustion volume.

According to an embodiment, a combustion system 2100 may include acombustion volume 2108 configured to support a flow stream including amixture of fuel and oxidizer ignited within the combustion volume 2108to generate a flame 2101 and an exhaust flow 2103 having a plurality ofcombustion particle classifications; and a charge source configured tosupply electrical charges into the exhaust flow. Additionally, it mayinclude a high voltage power supply (HVPS) 2110 configured to apply anelectrical potential having a first polarity to the charge source; and acollector plate 2102 including an electrical conductor coupled toreceive an electrical potential having a second polarity from a nodeoperatively coupled to the HVPS 2110.

The collector plate 2102 may be disposed above and away from thecombustion volume 2108 distal to the flame 2101 and arranged to cause atleast one combustion particle classification to flow to a collectionlocation and to cause at least one different combustion particleclassification to flow to one or more locations different from thecollection location. The charge source may include one or more shapedelectrodes 2106.

In an embodiment, the one or more shaped electrodes 2106 may bepositioned within the combustion volume 2108 above and to a side of theflame 2101 and adjacent to the exhaust flow 2103. Additionally, the oneor more shaped electrodes 2106 may be tapered to a sharp tip directedinto the exhaust flow 2103. In an embodiment, the one or more shapedelectrodes 2106 may generate a corona discharge proximate to the sharptip. The corona discharge may, in turn, generate an ionic wind 2114passing through the exhaust flow 2103. The ionic wind 2114 may be partlyresponsible for causing the at least one combustion particleclassification to flow to the collection location. The corona dischargemay be selected to cause a charge to attach to all or most of theplurality of combustion particle classifications.

In an embodiment, the collector plate 2102 may include an electricallyconductive surface proximate to the exhaust flow 2103. The electricallyconductive surface may include a metal, such as iron, steel, copper,silver or aluminum, or alloys of each, wherein the preponderantconstituent of the alloy consists of iron, steel, copper, silver oraluminum.

According to an embodiment, the combustion system may further include adirector conduit 2202 configured to receive the flow of the at least onecombustion particle classification at the collection location and toconvey the flow of at the least one combustion particle classificationto an output location. The director conduit 2202 may include an inletport disposed above the combustion volume 2108 proximate the collectionlocation, an outlet port disposed adjacent the combustion volume 2108proximate the flame 2101, and a hollow body connecting the inlet andoutlet ports. The director conduit 2202 may further include a fan,impeller or vacuum means 2204 to provide an additional dragging force onthe first combustion particle classification through the hollowconnecting body from the inlet port to the outlet port. The outputlocation may be selected to cause the flow of the at least onecombustion particle classification to flow toward the flame 2101. Thedirector conduit 2202 may include a dielectric or insulator material,such as elastomeric foam, fiberglass, ceramics, refractory brick,alumina, quartz, fused glass, silica, VYCOR™, and combination thereof.

According to an embodiment, a combustion system 2200 may include acombustion volume 2108 configured to support a flow stream including amixture of fuel and oxidizer ignited within the combustion volume 2108to generate a flame 2101 and an exhaust flow 2103 having a plurality ofcombustion particle classifications; and a charge source configured tosupply electrical charges into the exhaust flow. The combustion systemmay further include a high voltage power supply (HVPS) 2110 configuredto apply an electrical potential having a first polarity to the chargesource, and a director conduit 2202 configured to receive a flow of atleast some portion of the plurality of combustion particleclassifications at a collection location and convey the flow of at theleast some portion of the plurality of combustion particleclassifications to an output location.

The charge source may include one or more shaped electrodes 2106, whichmay be positioned above and to a side of the flame 2101 and adjacent tothe exhaust flow 2103. The one or more shaped electrodes 2106 aretapered to a sharp tip directed into the exhaust flow 2103. The one ormore shaped electrodes 2106 may be configured to generate a coronadischarge proximate to the sharp tip. The corona discharge may, in turn,generate an ionic wind 2114 passing through the exhaust flow 2103. Theionic wind 2114 may be partly responsible for causing at least someportion of the plurality of combustion particle classifications to flowto the collection location. The corona discharge may be selected tocause a charge to attach on to all or most of the plurality ofcombustion particle classifications.

According to an embodiment, the director conduit 2202 may include aninlet port disposed above the combustion volume 2108 proximate thecollection location, an outlet port disposed adjacent the combustionvolume 2108 proximate the flame 2101, and a hollow body connecting theinlet and outlet ports. The director conduit 2202 may further include afan, impeller or vacuum means 2204 to provide an additional draggingforce on the first combustion particle classification through the hollowconnecting body from the inlet port to the outlet port. In anembodiment, the output location may be selected to cause the flow of theat least one combustion particle classification to flow toward the flame2101. The director conduit 2202 may include a dielectric or insulatormaterial, such as elastomeric foam, fiberglass, ceramics, refractorybrick, alumina, quartz, fused glass, silica, VYCOR™, and combinationthereof.

According to an embodiment, a combustion system may further include oneor more sensors 2404 in electrical communication with a programmablecontroller 2402. The one or more sensors 2404 may each provide aplurality of time-sequenced sensor inputs to the programmablecontroller. The programmable controller may be configured to change theelectrical potential applied by the HVPS 2110 to the one or more shapedelectrodes 2106 from time-to-time based on a comparison of the pluralityof time-sequenced sensor inputs received by the programmable controller2402 against a set of one or more predetermined values preprogrammedonto the programmable controller 2402.

According to an embodiment, a method for reducing the size and number ofparticles entrained within an exhaust flow leaving a combustion systemmay include applying a first electrical potential to one or more shapedelectrodes positioned above a flame within a combustion volume andadjacent to the exhaust flow an exhaust flow including a plurality ofburned and unburned particles leaving the combustion volume. A coronadischarge may be generated proximate to the shaped electrodes, therebyproviding an ionic wind including a plurality of electric chargespassing through the exhaust flow. In an embodiment, at least some of theelectric charge having a first polarity may be deposited onto at least aportion of the plurality of burned and unburned particles therebyproviding a plurality of charged particles.

According to an embodiment, an electrically conductive collector platemay be provided. The collector plate may be disposed above and away fromthe combustion volume distal to the flame.

According to an embodiment, a second electrical potential may be appliedto the electrically conductive collector plate, the second electricalpotential having a polarity which is opposite that of the firstpolarity, wherein at least a fraction of the plurality of chargedparticles is collected at a surface of the collector plate.

According to an embodiment, generating a corona discharge proximate tothe shaped electrodes may include providing shaped electrodes that aretapered to a sharp tip. Generating a corona discharge proximate to theshaped electrodes may further include generating a high voltagepotential proximate to the sharp tip. The ionic wind may be partlyresponsible for causing the fraction of the plurality of the chargedparticles to flow to the surface of the collector plate. The collectorplate may include an electrically conductive surface proximate to theexhaust flow. In an embodiment, the electrically conductive surface mayinclude a metal, such as iron, steel, copper, silver or aluminum, oralloys of each, wherein the preponderant constituent of the alloyconsists of iron, steel, copper, silver or aluminum.

According to an embodiment, the method further include providing adirector conduit configured to receive a flow of some portion of theplurality of burned and unburned particles at an input location and toconvey the flow to an output location. The director conduit may includean inlet port disposed above the combustion volume proximate the inputlocation disposed away from the collection plate, an outlet portdisposed adjacent the combustion volume proximate the flame, and ahollow body connecting the inlet and outlet ports. The director conduitmay further include a fan, impeller or vacuum means to provide anadditional dragging force on at least some of the plurality of burnedand unburned particles through the hollow connecting body from the inletport to the outlet port. The output location may be selected to causethe flow of the at least some of the plurality of burned and unburnedparticles to flow toward the flame. In an embodiment, the directorconduit may include a dielectric or insulator material, such aselastomeric foam, fiberglass, ceramics, refractory brick, alumina,quartz, fused glass, silica, VYCOR™, and combination thereof.

According to an embodiment, the method may further include providing adirector conduit having an inlet port disposed above the combustionvolume, an outlet port disposed adjacent to the flame, a tubular bodybetween the inlet and outlet ports, and a fan, impeller or vacuum meansfor drawing some portion of the exhaust flows through the tubular bodythereby redirecting some portion of the burned and unburned particlesnot captured by the collector plate back into the combustion volume. Themethod may further include providing one or more sensors in electricalcommunication with a programmable controller. The one or more sensorsmay each be providing a plurality of time-sequenced sensor inputs to theprogrammable controller. The programmable controller may change theelectrical potential applied by the HVPS to the one or more shapedelectrodes from time-to-time based on a comparison of the plurality oftime-sequenced sensor inputs received by the programmable controlleragainst a set of one or more predetermined values preprogrammed onto theprogrammable controller.

The various systems, apparatuses, burners, devices, processes, andmethods disclosed in FIGS. 1-32 can be combined to provide otherembodiments. As an example, the combustion apparatuses 100 and 200 ofFIG. 1 and FIG. 2 can implement the electrodes 2106, the collector 2102,and the voltage source 2110 and other components of FIGS. 28-31 in orderto remove collect, trap, draw away, and/or remove portions of an exhaustor flue gas from the combustion reaction 150 and/or the combustionreaction 115. For example, the electrodes 2106, can be positioned abovethe second combustion reaction 150 of FIG. 1 in order to inject chargedparticles into an exhaust stream or flue gas stream. The collector 2102can be positioned above and lateral from the combustion reaction 150 andcan act as a field electrode to attract exhaust or flue gas particles.The conduit 2202 can also be positioned to act as a field electrode toattract exhaust particles from the second combustion reaction 150.

With reference to FIGS. 1-3, 28-32, according to an embodiment, a methodfor operating a combustion system, includes outputting a first fuel anda first oxidant, supporting a first combustion reaction 115 with thefirst fuel and first oxidant, supporting a second combustion reaction150 of the heated second fuel to the produce a flue gas includingentrained particles. The method further includes providing an electricalcharge to the second combustion reaction 150, wherein the electricalcharge is carried by the entrained particles, supporting a first fieldelectrode, such as the collector 102, adjacent to a main flow of theflue gas and applying a first voltage to the first field electrode. Themethod also includes electrostatically attracting the entrainedparticles toward the first field electrode to remove at least a portionof the entrained particles from a main flow of the flue gas.

According to an embodiment the first voltage is opposite in polarity tothe electrical charge provided to the second combustion reaction 150.According to an embodiment, providing the electrical charge to thesecond combustion reaction 150 includes applying a voltage to a grate135 supporting the second fuel 145 and transferring charges from thegrate 135 to the second fuel 145. According to an embodiment, the grateincludes a crucible. According to an embodiment, providing theelectrical charge to the second combustion reaction 150 includesoperating an ionizer, for example including electrodes 106, to applycharges to the first combustion reaction 150. According to anembodiment, the method includes outputting a second oxidant proximal tothe second fuel. According to an embodiment providing the electricalcharge to the second combustion reaction includes operating an ionizer2106 to apply charges to the second oxidant. According to an embodiment,the method includes

According to an embodiment the method includes providing a second fieldelectrode, for example the director conduit 2202, disposed injuxtaposition to the first field electrode and applying a second voltagedifferent than the first voltage to the second field electrode to forman electric field between the first and second field electrodes.According to an embodiment, the first field electrode includes aplurality of conductors disposed across the main flow of the flue gasand wherein the second field electrode includes a plurality ofconductors interlineated with the first electrode plurality ofconductors.

According to an embodiment, the second voltage is opposite in polarityto the first voltage. According to an embodiment, the method includesproviding a secondary flue gas flow different than the first flue gasflow adjacent to the first field electrode, and entraining theelectrostatically attracted particles in the secondary flue gas flow.The method can further include directing the secondary flue gas flow andentrained electrostatically attracted particles toward the first orsecond combustion reaction 115, 150. Removing the entrainedelectrostatically attracted particles from the secondary flue gas flowcan include filtering the secondary flue gas flow.

With reference to FIGS. 1-3, 28-32 a co-fired combustion apparatusincludes a first fuel-introduction body 105 configured to provide afirst fuel to a first combustion reaction 115 and a secondfuel-introduction body 135 configured to provide a second fuel to asecond combustion reaction 150, wherein the second combustion reactionemits an exhaust flow having a plurality of combustion particleclassifications and wherein the first fuel introduction body 105 ispositioned relative to the second fuel introduction body 135 to causethe first combustion reaction to at least intermittently provide heat tothe second combustion reaction 150. The apparatus further includes anelectrode assembly 160 associated with the second fuel introduction body135 or a second combustion volume to which the second fuel introductionbody 135 provides the second fuel, the electrode assembly 160 beingconfigured to be driven to or maintained at one or more first voltagesselected to provide an electric field to the second combustion volume.The apparatus further includes a charge source, for example electrodes2106, configured to supply electrical charges into the exhaust flow anda high voltage power supply 2110 (HVPS) configured to apply anelectrical potential having a first polarity to the charge source. Theapparatus further includes a collector plate 2102 including anelectrical conductor coupled to receive an electrical potential having asecond polarity from a node operatively coupled to the HVPS, thecollector plate 102 disposed above and a distal to the second combustionreaction 150 and arranged to cause at least one combustion particleclassification to flow to a collection location and to cause at leastone different combustion particle classification to flow to one or morelocations different from the collection location.

According to an embodiment, the electrode assembly includes one or moreelectrodes proximate or within the second combustion region. Accordingto an embodiment, the electrode assembly 160 includes the secondfuel-introduction body 145.

According to an embodiment, a portion of the apparatus is enclosedwithin a housing 120. According to an embodiment, a portion of thehousing 120 is operable to be driven to or held at one or more secondvoltages. According to an embodiment, the electrode assembly 160includes a portion of the housing 120.

According to an embodiment, the second fuel-introduction body 135includes a crucible assembly configured to support the second fuel. Theelectrode assembly 160 may include the crucible assembly.

According to an embodiment, the first fuel-introduction body 105includes a burner assembly. The first fuel-introduction body 105 may beconfigured to be driven to or held at one or more second voltages.

According to an embodiment, the electrode assembly 160 associated withthe second combustion region is operable to increase combustionefficiency of the second combustion reaction 150 when the electrodeassembly 160 is driven to or held at the one or more first voltages.

According to an embodiment, the second combustion reaction 150 producesa combustion product stream having a flow and the electrode assemblyassociated with the second combustion region is operable to generate acombustion product stream flow having turbulent flow when the electrodeassembly 160 is driven to or held at the one or more first voltages.

According to an embodiment, the first fuel is substantially liquid orgaseous. According to an embodiment, the second fuel is substantiallysolid. According to an embodiment, the second fuel forms a portion of afluidized bed.

According to an embodiment, the apparatus includes a stoker configuredto introduce the second fuel to the second combustion region.

According to an embodiment, a portion of the apparatus is enclosedwithin a flue, stack, or pipe configured to convey a combustion productstream generated by at least the second combustion.

According to an embodiment, the first fuel includes at least one ofnatural gas, propane, butane, coal, or oil. According to an embodiment,the second fuel includes one or more of rubber, wood, glycerin, anindustrial waste stream, a post-consumer waste stream, an industrialby-product, garbage, hazardous waste, human waste, animal waste, animalcarcasses, forestry residue, batteries, tires, waste plant material, orlandfill waste.

According to an embodiment, the co-fired combustion apparatus furtherincludes a first burner assembly configured to support the firstcombustion and a burner support configured to support the first burnerassembly in a housing.

According to an embodiment, the charge source includes one or moreshaped electrodes 2106. According to an embodiment, the one or moreshaped electrodes 2106 are positioned within the combustion volume aboveand to a side of the second combustion reaction 150 and adjacent to theexhaust flow. According to an embodiment, the one or more shapedelectrodes 106 are tapered to a sharp tip directed into the exhaustflow. The one or more shaped electrodes may generate a corona dischargeproximate to the sharp tip. The corona discharge may generate an ionicwind 2114 passing through the exhaust flow.

According to an embodiment, the ionic wind 2114 is partly responsiblefor causing the at least one combustion particle classification to flowto the collection location 2102. According to an embodiment, the coronadischarge is selected to cause a charge to attach to all or most of theplurality of combustion particle classifications.

According to an embodiment, the collector plate 2102 includes anelectrically conductive surface proximate to the exhaust flow. Theelectrically conductive surface may include a metal. According to anembodiment, the metal is iron, steel, copper, silver or aluminum, oralloys of each, wherein the preponderant constituent of the alloyconsists of iron, steel, copper, silver or aluminum.

According to an embodiment, the co-fired apparatus includes a directorconduit 2202 configured to receive the flow of the at least onecombustion particle classification at the collection location and toconvey the flow of at the least one combustion particle classificationto an output location. The director conduit 2202 may include an inletport disposed above the combustion volume proximate the collectionlocation, an outlet port disposed adjacent the combustion volumeproximate the flame, and a hollow body connecting the inlet and outletports.

According to an embodiment, the director conduit 2202 further includes afan 2204, impeller or vacuum means to provide an additional draggingforce on the first combustion particle classification through the hollowconnecting body from the inlet port to the outlet port. According to anembodiment, the output location is selected to cause the flow of the atleast one combustion particle classification to flow toward the flame.The director conduit 2202 includes a dielectric or insulator material.According to an embodiment, the dielectric or insulator material isselected from the list consisting of elastomeric foam, fiberglass,ceramics, refractory brick, alumina, quartz, fused glass, silica,VYCOR™, and combination thereof.

Finally, while various aspects and embodiments have been disclosedherein, other aspects and embodiments are contemplated. The variousaspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting, with the true scope and spirit beingindicated by the claims.

1. A method for operating a combustion system, comprising: outputting afirst fuel and a first oxidant; supporting a first combustion reactionwith the first fuel and first oxidant; supporting a second combustionreaction of a heated second fuel to the produce a flue gas includingentrained particles; providing an electrical charge to the secondcombustion reaction, wherein the electrical charge is carried by theentrained particles; supporting a first field electrode adjacent to amain flow of the flue gas; applying a first voltage to the first fieldelectrode; and electrostatically attracting the entrained particlestoward the first field electrode to remove at least a portion of theentrained particles from a main flow of the flue gas.
 2. The method ofclaim 1, wherein the first voltage is opposite in polarity to theelectrical charge provided to the second combustion reaction.
 3. Themethod of claim 1, wherein providing the electrical charge to the secondcombustion reaction includes applying a voltage to a grate supportingthe second fuel and transferring charges from the grate to the secondfuel.
 4. The method of claim 3, wherein the grate comprises a crucible.5. The method of claim 1, wherein providing the electrical charge to thesecond combustion reaction includes operating an ionizer to applycharges to the first combustion reaction.
 6. The method of claim 1,further comprising: outputting a second oxidant proximal to the secondfuel.
 7. The method of claim 6, wherein providing the electrical chargeto the second combustion reaction includes operating an ionizer to applycharges to the second oxidant.
 8. The method of claim 1, furthercomprising: providing a second field electrode disposed in juxtapositionto the first field electrode; and applying a second voltage differentthan the first voltage to the second field electrode to form an electricfield between the first and second field electrodes.
 9. The method ofclaim 8, wherein the first field electrode comprises a plurality ofconductors disposed across the main flow of the flue gas; and whereinthe second field electrode comprises a plurality of conductorsinterlineated with the first electrode plurality of conductors.
 10. Themethod of claim 8, wherein the second voltage is opposite in polarity tothe first voltage.
 11. The method of claim 1, further comprising:providing a secondary flue gas flow different than the first flue gasflow adjacent to the first field electrode; and entraining theelectrostatically attracted particles in the secondary flue gas flow.12. The method of claim 11, further comprising: directing the secondaryflue gas flow and entrained electrostatically attracted particles towardthe first or second combustion reaction.
 13. The method of claim 11,further comprising removing the entrained electrostatically attractedparticles from the secondary flue gas flow by filtering the secondaryflue gas flow.
 14. A co-fired combustion apparatus, comprising: a firstfuel-introduction body configured to provide a first fuel to a firstcombustion reaction; a second fuel-introduction body configured toprovide a second fuel to a second combustion reaction, wherein thesecond combustion reaction emits an exhaust flow having a plurality ofcombustion particle classifications and wherein the first fuelintroduction body is positioned relative to the second fuel introductionbody to cause the first combustion reaction to at least intermittentlyprovide heat to the second combustion reaction; and an electrodeassembly associated with the second fuel introduction body or a secondcombustion volume to which the second fuel introduction body providesthe second fuel, the electrode assembly being configured to be driven toor maintained at one or more first voltages selected to provide anelectric field to the second combustion volume; a charge sourceconfigured to supply electrical charges into the exhaust flow; a highvoltage power supply (HVPS) configured to apply an electrical potentialhaving a first polarity to the charge source; a collector plateincluding an electrical conductor coupled to receive an electricalpotential having a second polarity from a node operatively coupled tothe HVPS, the collector plate disposed above and a distal to the secondcombustion reaction and arranged to cause at least one combustionparticle classification to flow to a collection location and to cause atleast one different combustion particle classification to flow to one ormore locations different from the collection location.
 15. The co-firedapparatus of claim 14, wherein the electrode assembly includes one ormore electrodes proximate or within the second combustion region. 16.The co-fired apparatus of claim 14, wherein the electrode assemblyincludes the second fuel-introduction body.
 17. The co-fired apparatusof claim 14, wherein a portion of the apparatus is enclosed within ahousing.
 18. The co-fired apparatus of claim 17, wherein a portion ofthe housing is operable to be driven to or held at one or more secondvoltages.
 19. The co-fired apparatus of claim 17, wherein the electrodeassembly comprises a portion of the housing.
 20. The co-fired apparatusof claim 14, wherein the electrode assembly comprises the secondfuel-introduction body.
 21. The co-fired apparatus of claim 14, whereinthe second fuel-introduction body comprises a crucible assemblyconfigured to support the second fuel.
 22. The co-fired apparatus ofclaim 21, wherein the electrode assembly comprises the crucibleassembly.
 23. The co-fired apparatus of claim 14, wherein the firstfuel-introduction body comprises a burner assembly.
 24. The co-firedapparatus of claim 14, wherein the first fuel-introduction body isoperable to be driven to or held at one or more second voltages.
 25. Theco-fired apparatus of claim 14, wherein the electrode assemblyassociated with the second combustion region is operable to increasecombustion efficiency of the second combustion when the electrodeassembly is driven to or held at the one or more first voltages.
 26. Theco-fired apparatus of claim 14, wherein the second combustion produces acombustion product stream having a flow; and wherein the electrodeassembly associated with the second combustion region is operable togenerate a combustion product stream flow having turbulent flow when theelectrode assembly is driven to or held at the one or more firstvoltages.
 27. The co-fired apparatus of claim 14, wherein the first fuelis substantially liquid or gaseous.
 28. The co-fired apparatus of claim14, wherein the second fuel is substantially solid.
 29. The co-firedapparatus of claim 15, wherein the second fuel forms a portion of afluidized bed.
 30. The co-fired apparatus of claim 14, furthercomprising a stoker configured to introduce the second fuel to thesecond combustion region.
 31. The co-fired apparatus of claim 14,wherein a portion of the apparatus is enclosed within a flue, stack, orpipe configured to convey a combustion product stream generated by atleast the second combustion.
 32. The co-fired apparatus of claim 14,wherein the first fuel includes at least one of natural gas, propane,butane, coal, or oil.
 33. The co-fired apparatus of claim 14, whereinthe second fuel includes one or more of rubber, wood, glycerin, anindustrial waste stream, a post-consumer waste stream, an industrialby-product, garbage, hazardous waste, human waste, animal waste, animalcarcasses, forestry residue, batteries, tires, waste plant material, orlandfill waste.
 34. The co-fired combustion apparatus of claim 14,further comprising: a first burner assembly configured to support thefirst combustion; and a burner support configured to support the firstburner assembly in a housing.
 35. The co-fired apparatus of claim 14,wherein the charge source includes one or more shaped electrodes. 36.The co-fired apparatus of claim 35, wherein the one or more shapedelectrodes are positioned within the combustion volume above and to aside of the flame and adjacent to the exhaust flow.
 37. The co-firedapparatus of claim 36, wherein the one or more shaped electrodes aretapered to a sharp tip directed into the exhaust flow.
 38. The co-firedapparatus of claim 37, wherein the one or more shaped electrodesgenerate a corona discharge proximate to the sharp tip.
 39. The co-firedapparatus of claim 38, wherein the corona discharge generates an ionicwind passing through the exhaust flow.
 40. The co-fired apparatus ofclaim 39, wherein the ionic wind is partly responsible for causing theat least one combustion particle classification to flow to thecollection location.
 41. The co-fired apparatus of claim 39, wherein thecorona discharge is selected to cause a charge to attach to all or mostof the plurality of combustion particle classifications.
 42. Theco-fired apparatus of claim 41, wherein the collector plate includes anelectrically conductive surface proximate to the exhaust flow.
 43. Theco-fired apparatus of claim 42, wherein the electrically conductivesurface includes a metal.
 44. The co-fired apparatus of claim 43,wherein the metal is iron, steel, copper, silver or aluminum, or alloysof each, wherein the preponderant constituent of the alloy consists ofiron, steel, copper, silver or aluminum.
 45. The co-fired apparatus ofclaim 44, further comprising a director conduit configured to receivethe flow of the at least one combustion particle classification at thecollection location and to convey the flow of at the least onecombustion particle classification to an output location.
 46. Theco-fired apparatus of claim 45, wherein the director conduit includes aninlet port disposed above the combustion volume proximate the collectionlocation, an outlet port disposed adjacent the combustion volumeproximate the flame, and a hollow body connecting the inlet and outletports.
 47. The co-fired apparatus of claim 45, wherein the directorconduit further includes a fan, impeller or vacuum means to provide anadditional dragging force on the first combustion particleclassification through the hollow connecting body from the inlet port tothe outlet port.
 48. The co-fired apparatus of claim 47, wherein theoutput location is selected to cause the flow of the at least onecombustion particle classification to flow toward the flame.
 49. Theco-fired apparatus of claim 45, wherein the director conduit includes adielectric or insulator material.
 50. The co-fired apparatus of claim49, wherein the dielectric or insulator material is selected from thelist consisting of elastomeric foam, fiberglass, ceramics, refractorybrick, alumina, quartz, fused glass, silica, VYCOR™, and combinationthereof.